Hi evh, welcome.
This is a difficult choice as they both have their challenges. A sub will prove to be very technical, even the 'simpler' models require a very careful build if they are to perform. A surface model has different build requirements but at least has more latitude to get something wrong/not quite right and still operate within satisfaction.
I have never built a submarine before, though i quite fancy the technical challenge of doing so. I fancy, however, that the first build will turn out to be no more than a"static" model.
